1. Technical Field of the Invention
The present invention relates generally to a laser beam inspection apparatus which inspects an electronic parts-fabricated substrate for defects, and more particularly to a laser beam inspection apparatus designed to monitor whether electronic parts or components are mounted in desired positions on a substrate or not and whether they are correct ones or not.
2. Background Art
Typical inspection apparatuses of the above type include a laser emitter radiating a laser beam onto each electronic component such as an IC mounted on a substrate, a laser receiver receiving a return of the laser beam from the electronic component, and an inspection circuit processing the return of the laser beam to obtain information about the appearance of the electronic component. Specifically, the inspection apparatuses of this type are designed to obtain the appearance information on the electronic components using the triangulation.
The above inspection apparatuses, however, have the drawback in that an inspection error may arise when the size of the electronic components is changed.
Specifically, the inspection apparatus first fixes a scan range in which a laser beam is to be radiated onto the substrate and then scans the laser beam in the scan range to determine the size of a target one of the electronic components and whether the target electronic component is mounted in a correct orientation or not. Therefore, in a case where a larger electronic component is inspected in the scan range which was determined when a smaller electronic component was inspected in a previous cycle, it may become impossible to scan the whole of an area of the larger electronic component including the tolerance, which leads to the inspection error.
Conversely, in a case where a smaller electronic component is inspected in the scan range which was determined when a larger electronic circuit component was inspected, it will cause the number of inspection points on the smaller electronic component to be decreased, thus resulting in an increase in resolution or a decrease in inspection accuracy.
It is therefore a principal object of the present invention to avoid the disadvantages of the prior art.
It is another object of the invention to provide an inspection apparatus capable of changing orientation of a scan of a laser beam and/or an area of a scan range as a function of the type of a target object to be inspected.
According to one aspect of the invention, there is provided an inspection apparatus which comprises: (a) a laser emitter emitting a laser beam for inspecting objects; (b) a scan mechanism moving the laser beam emitted from the laser emitter to scan a target one of the objects in a given scan range, the scan mechanism being designed to change orientation of emission of the laser beam to change the scan range; and (c) a laser receiver receiving a return of the laser beam from the target object to provide an object-inspected data.
In the preferred mode of the invention, the scan mechanism includes refracting members arranged adjacent each other along an optical path of the laser beam emitted from the laser emitter.
The refracting members may be made of flat plates.
The scan mechanism works to rotate the refracting members in the same direction about a given axis of rotation to achieve circular scanning of the laser beam.
The scan mechanism holds a given relative angle between the refracting members and rotates the refracting members to achieve the circular scanning of the laser beam in the scan range.
The scan mechanism includes an angle changing mechanism designed to change the relative angle between the refracting members to change the scan range and rotates the refracting members while keeping the relative angle to achieve the circular scanning of the laser beam in the changed scan range.
The angle changing mechanism changes a speed of rotation of one of the refracting members to change the scan range.
A moving mechanism is further provided which is designed to move the inspection apparatus from one of the objects to another having a different size after completion of a scan of the one of the objects. The angle changing mechanism changes the relative angle between the refracting members during movement of the inspection apparatus.
The scan mechanism may rotate the refracting members in opposite directions synchronously about the given axis of rotation to achieve rectilinear scanning of the laser beam in which a spot of the laser beam moves along a straight scan path.
The angle changing mechanism changes the relative angle between the refracting members to change orientation of the rectilinear scanning.
The objects to be inspected may be electronic components each made up of a body and a lead extending from the body. In this case, the scan mechanism rotates the refracting members made up of flat plates in the same direction synchronously about the given axis of rotation to achieve the circular scanning of the laser beam when the body of each of the electronic components is inspected. The angle changing mechanism changes and keeps the relative angle between the refracting members at 180xc2x0 to achieve movement of the laser beam linearly when the lead is inspected.
The angle changing mechanism may change and rotate the refracting members in the opposite directions synchronously while keeping the relative angle between the refracting members at a given value to perform the rectilinear scanning of the laser beam when the lead is inspected.
According to another aspect of the invention, there is provided an inspection apparatus which comprises: (a) a laser emitter emitting a laser beam for inspecting objects; (b) a scan mechanism subjecting the laser beam emitted from the laser emitter to circular motion to scan a target one of the objects in a circular scan range cyclically, the scan mechanism being designed to control orientation of emission of the laser beam to determine an area of the circular scan range as a function of the size of the target object; and (c) a laser receiver receiving a return of the laser beam from the target object to provide an object-inspected data.
According to the third aspect of the invention, there is provided an inspection apparatus which comprises: (a) a laser emitter emitting a laser beam for inspecting objects; (b) a scan mechanism including refracting members disposed adjacent to each other along an optical path of the laser beam to change orientation of emission of the laser beam emitted from the laser emitter to perform rectilinear scanning about a target one of the objects, the scan mechanism being designed to change a relative angle between the refracting members to change orientation of the rectilinear scanning of the laser beam as a function of orientation of the target object; and (c) a laser receiver receiving a return of the laser beam from the target object to provide an object-inspected data.